Communication devices such as terminals or wireless devices are also known as e.g. User Equipments (UEs), mobile terminals, wireless terminals and/or mobile stations. Such terminals are enabled to communicate wirelessly in a wireless communication system or a cellular communications network, sometimes also referred to as a cellular radio system or cellular networks. The communication may be performed e.g. between two wireless devices, between a wireless device and a regular telephone and/or between a wireless device and a server via a Radio Access Network (RAN) and possibly one or more core networks, comprised within the wireless communications network.
The above terminals or wireless devices may further be referred to as mobile telephones, cellular telephones, laptops, or tablets with wireless capability, just to mention some further examples. The terminals or wireless devices in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the RAN, with another entity, such as another terminal or a server.
The cellular communications network covers a geographical area which is divided into cell areas, wherein each cell area being served by an access node such as a base station, e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g. “eNB”, “eNodeB”, “NodeB”, “B node”, “gNB”, “gNodeB”, or Base Transceiver Station (BTS), depending on the technology and terminology used. The base stations may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the base station at a base station site. One base station, situated at the base station site, may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the terminals or wireless devices within range of the base stations. In the context of this disclosure, the expression Downlink (DL) is used for the transmission path from the base station to the mobile station. The expression Uplink (UL) is used for the transmission path in the opposite direction i.e. from the mobile station to the base station.
In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), base stations, which may be referred to as eNodeBs or even eNBs, may be directly connected to one or more core networks.
The 3GPP LTE radio access standard has been written in order to support high bitrates and low latency both for uplink and downlink traffic. All data transmission is in LTE controlled by the radio base station.
The E-UTRA is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. It is an acronym for evolved UMTS Terrestrial Radio Access, also referred to as the 3GPP work item on the Long Term Evolution (LTE) also known as the Evolved Universal Terrestrial Radio Access (E-UTRA) in early drafts of the 3GPP LTE specification. E-UTRAN is the initialism of Evolved UMTS Terrestrial Radio Access Network and is the combination of E-UTRA, UEs and eNodeBs.
Quality of Service (QoS)
In E-UTRA, Quality of Service is achieved by mapping packets that require different treatment onto different radio bearers. Subsequently, the communications network and the wireless device, e.g. the UE, serve these radio bearers so that the packets mapped to said bearers observe the quality of service, e.g. delay, loss rate, etc., configured for that service and bearer.
In LTE the mapping of packets to radio bearers is achieved by packet filters. These packet filters allow filtering of packets by at least one of a source address, a destination address, a source port number, a destination port number and a protocol type. For example, a filter may match to packets indicating a certain source address in their IP header, i.e., all packets originating from a certain server. Or a filter may be configured to match all packets going to a particular port number.
In E-UTRA, packet filters are configured in the packet gateway for filtering downlink packets. Furthermore, packet filters are configured in the UE for filtering uplink packets. The filters in the UE are configured by the core network via the Non-Access-Stratum (NAS) protocol layer. The packet filters are associated with Evolved Packet System (EPS) Bearers so that a packet matching a filter is mapped to and transmitted on said associated EPS bearer. For a UE with an established RRC connection, each EPS bearer is mapped to an S1 bearer and to a radio bearer. The S1 bearer determines a path from the Core Network (CN) to the RAN, e.g. by means of the eNB, and the radio bearer determines a logical channel between the eNB and the UE.
For a New Radio (NR) interface, the core network is not expected to map packets to EPS bearers but rather to mark them with a Flow ID and/or a Flow Priority ID (FPI). The RAN, e.g. by means of the eNB, i.e. the gNB, and the UE may use said Flow ID and/or FPI to determine the radio bearer to which the packets should be mapped on the radio interface. Hence, in NR the radio bearer establishment as well as the mapping of higher layer packets to said radio bearers is left to the RAN, e.g. by means of the eNB.
It is envisioned that, similarly to E-UTRA, the eNB may provide the UE with a set of packet filters and thereby control which uplink packets the UE shall map to which radio bearer. For the downlink direction, e.g. from the eNB to the UE, the mapping of packets to radio bearers is up to eNB implementation and does not need to be configured and/or indicated to the UE a priori.
Besides such explicit configuration of uplink packet filters it is also being discussed that the UE may derive the uplink packet filters based on the downlink packets received on a plurality of radio bearers. This is referred to as “reflective QoS” and is described in the following section.
Reflective QoS
For the NR interface, the radio network, e.g. by means of the evolved Node B, eNB, may establish Data Radio Bearers (DRBs) and map selected downlink packets onto these DRBs. Instead of configuring the UE with uplink packet filters, the NR interface may also provide the possibility to command the UE to create so-called “reflective filters”. The UE inspects received downlink packets and creates filters based on certain criteria and use these filters subsequently to filter corresponding uplink packets. For example, the UE may detect the flow IDs of all downlink packets received on a particular radio bearer and create a corresponding filter that identifies all uplink packets with the same flow ID and maps those onto the same radio bearer on which it previously received said downlink packets.
The packet filters configured explicitly by the communications network, e.g. by the CN or the RAN, enable a very accurate and deterministic filtering of packets, e.g. data packets, onto bearers, e.g. radio bearers. However, depending on the traffic characteristics, this scheme may require frequent reconfiguration of the filters which would cause a lot of control signalling on the radio interface and processing load in the RAN and/or the CN.
On the other hand, the “reflective QoS” mechanism aims to reduce the signalling load but can only be applied to uplink packets if corresponding downlink packets have been received previously. For some traffic the “reflective filter” created based on the observed downlink data may also not result in the desired uplink packet filtering. Hence, “reflective filters” alone cannot address all use cases and requirements.